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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

What has global warming done since 1998?

What the science says...

Every part of the Earth's climate system has continued warming since 1998, with 2015 shattering temperature records.

Climate Myth...

It hasn't warmed since 1998
For the years 1998-2005, temperature did not increase. This period coincides with society's continued pumping of more CO2 into the atmosphere. (Bob Carter)

Even if we ignore long term trends and just look at the record-breakers, 2015, 2014, 2010, and 2005 were hotter than 1998.

The myth of no warming since 1998 was based on the satellite record estimates of the temperature of the atmosphere. However, as discussed in the video below by Peter Sinclair, even that argument is no longer accurate. The satellites show warming since 1998 too.

To claim global warming stopped in 1998 also overlooks a simple physical reality - the land and atmosphere are just a small fraction of the Earth's climate (albeit the part we inhabit). The entire planet is accumulating heat due to an energy imbalance. The atmosphere is warming. Oceans are accumulating energy. Land absorbs energy and ice absorbs heat to melt. To get the full picture on global warming, you need to view the Earth's entire heat content. More than 90% of global warming heat goes into warming the oceans, while less than 3% goes into increasing the atmospheric and surface air temperatures. Nuccitelli et al. (2012) showed that the Earth has continued to heat up since 1998.

In 1998, an abnormally strong El Niño caused heat transfer from the Pacific Ocean to the atmosphere. Consequently, we experienced above average surface temperatures. Conversely, the 2000s saw predominantly La Niña conditions, which had a cooling effect on global temperatures. As a result, the warming of atmosphere and surface temperatures temporarily slowed. They've now started to speed up again, and the planet as a whole has kept on heating up the whole time.

Using moving averages to discern the long-term trend

With so much internal variability, scientists employ statistical methods to discern long-term trends in surface temperature. The easiest way to remove short-term variations, revealing any underlying trend, is to plot a moving average, performed in Waiting for Cooling (Fawcett & Jones 2008) . Figure 3 displays the 11-year moving average - an average calculated over the year itself and five years either side. They've used three different data-sets - NCDC, NASA GISS and the British HadCRUT3. In all three data-sets, the moving average shows no sign that the warming trend has reversed.

The linear trend since 1997 or 1998

Next, Fawcett and Jones look for a cooling trend in the 10 years since 1998. They find the linear trend over 1998 to 2007 is a warming trend in all three data-sets. Note that HadCRUT3 displays less warming than NASA GISS and NCDC. This is most likely due to the fact that HadCRUT data doesn't cover parts of the Arctic where there has been strong warming in recent years.

Figure 3: Linear trends (solid lines) in the three global annual mean temperature anomaly time series over the decade 1998-2007.

Cowtan & Way (2013) also evaluates global surface warming across the globe by using a statistical method known as 'kriging' andby using satellite data to fill in the gaps where there are no temperature stations. Their study shows that the global surface warming trend for 1997–2015 is approximately 0.14°C per decade.

Removing El Niño and other Exogeneous Factors

In addition to removing the ENSO signlal, Foster and Rahmstorf (2011) used multiple linear regression to remove the effects of solar and volcanic activity from the surface and lower troposphere temperature data. Their results are shown in the animation below.

Figure 4: Five data sets (GISS, NCDC, HadCRU, UAH, and RSS) with and without the effects of ENSO, solar irradiance, and volcanic emissions removed. Data from Foster and Rahmstorf 2011, animation created by Dana Nuccitelli.

When removing these short-term effects, the warming trend has barely even slowed since 1998 (0.163°C per decade from 1979 through 2010, vs. 0.155°C per decade from 1998 through 2010, and 0.187°C per decade for 2000 through 2010).

Summary

To sum up, every component of the Earth's climate has continued to warm since 1998. The myth of no warming during that time was based on the satellite record of atmospheric temperatures, which now shows warming. Surface and ocean temperatures have risen, as have sea levels, while ice has melted, spring is starting earlier, and so on. 2015 was hotter than 2010, which was hotter than 2005, which was hotter than 1998. A monster El Niño event made 1998 relatively hot at the surface and in the atmosphere, but Earth has continued warming rapidly over the past 18 years.

Further viewing

Comments

While I don't disagree with the statement that the overall warming trend continues, the line-of-best-fit-graph is a bit disingenuous. You should show the 2 sigma bounds on the fit line, which would likely show that the probability of no increase in the last 10 years is not unreasonable.

Further I presume that you used least-squares to fit the line. This assumes that temperature anomalies are normally distributed. Glancing at the graph, this doesn't seem to be the case (several major excursions from the mean trend line), so the outliers will unduly influence the line of best fit. Least squares is extremely non-robust to non-normal data.

The second graph doesn't help your argument much, and might actually hinder it some. If you could send me or point me to the raw data, I'd be happy to do a different analysis on it and see if there is a meaningful trend in the data.

These posts are useful. plfreeman, there's enough data from monthly, weekly, or daily summaries, that the regression and correlation are both statistically significant, even after correcting for autocorrelation and using various methods. Here's a good link to check it out, by a mathematician specializing in time series analysis:http://tamino.wordpress.com/2007/08/31/garbage-is-forever/

The strong version of Carter's claim that warming stopped in 1998 requires the slope to be zero or negative since then. It isn't, therefore the strong version is proven false (and the 60 individuals who signed that have demonstrated their commitment to ideology over data). Even the weak version ('no significant warming') is shown false.

According to Carter the slope is indeed negative since then. However, I believe he is quite clear in saying the amount is not really significant.

The data above does not match the data set he is using.

Response: I have corresponded with Bob Carter about the data he uses - in articles where he states the temperature trend is negligible or even cooling, he's erroneously using upper troposphere data. See the footnote of Satellites show no warming.

Plotting the two temperature records for the last 10 years shows that:
· The surface record showed a linear increase of 0.062 degrees C per decade
· The satellite record showed a linear increase of 0.059 degrees C per decade

The two warmest years during this period were 1998 (a strong ENSO year) and 2005 (a somewhat weaker ENSO year).

Both of these rates of increase are considerably lower than the average rate of increase over the past 28 years, when satellite readings first became available:
· The surface record showed a linear increase of 0.171 degrees C per decade
· The satellite record showed a linear increase of 0.142 degrees C per decade

Bob Carter’s article is almost 18 months old now, and we now have temperature records for both 2006 and 2007.

Interestingly, both years were predicted to be “record warm” years, with the usual media hype about this being additional proof of alarming global warming caused by man.

Both turned out to be rather normal years, but there was not much media hype, since (as we all know) “good news is no news”.

But as I showed earlier, if we compare the past decade we see that there is still warming, but that the rate has slowed down considerably in comparison with the earlier record.

Sure, there are two ENSO years in the record, 1998 and 2005 (which also turn out to be the two warmest years). But, then again, there will always be ENSO years and scientists have been unable to predict when these will occur or explain exactly why they occur when they do.

The question that this site raised should not have been whether or not it has warmed since 1998 but rather whether or not the rate of warming has decreased since 1998 as compared to earlier decades, and if so, whether or not this indicates a trend of slowdown in temperature increase or just an anomaly caused by individual ENSO years.

Good evening. Maybe this discussion could be enriched with comments from the IPCC chairman Rajenda Pachauri and the United Kingdom's Meteorological office (Royal, I presume).

From a recent Reuters' piece: "Rajenda Pachauri, the head of the U.N. Panel that shared the 2007 Nobel Peace Prize with former U.S. Vice President Al Gore, said he would look into the apparent temperature plateau so far this century.

"One would really have to see on the basis of some analysis what this really represents," he told Reuters, adding "are there natural factors compensating?" for increases in greenhouse gases from human activities."

And then the Met office. They recently issued a forecast for 2008, stating this much: "The forecast value for 2008 mean temperature is considered indistinguishable from any of the years 2001-2007, given the uncertainties in the data." Source: http://tinyurl.com/2ezepk

So, the IPCC is looking into "the plateau", and the Met Office says it persists into its' eight year, and who knows, after another eight years it may be very very cold again. Over at Tamino's Open mind there was some discussion about whether we should set 2015 as the year when the science could be declared settled;-). But the details seem to take some time to agree upon. The problem with outliers!

With no major volcanic outbreak since 1991, current temperatures are the same as before that major outbreak (Pinatabu). (Actually, current temperature is lower than then but it is fair to allow for a lower average temperature the years before Pinatabu and we need to keep in mind that current temperatures are a bit lower than previous years.)

Anyhow we can conclude than since prior to Pinatabu there has been no statistically significant warming trend (its all within error bounds).

Now how much was the upper projection of the IPCC? +6°C to the year 2100. From now on that roughly means at least five times the warming rate we've seen so far since satellite measurements began and more than ten times the warming rate since we started to increase our CO2 emissions (around 1940-45). That anyone can believe this without the IPCC presenting any evidence at all is flabbergasting to be honest.

I'll admit that there is a risk (albeit minor IMHO) for a two degree warming, but such a risk you handle differently and you certainly won't scare children nor keep people in poverty because of it.

OK, so now we have the data from the ARGO measuring system, and they show that the oceans have not warmed at all since 2003. So there is more than just one La Nina behind the flattening of global temperatures, wouldn't you agree?

Compared to the average 1998 through 2007:
The average for the first 5 months of 2008 is 0.16°C colder according to Hadley's HADcrut3, and 0.10°C colder according to NOAA while the atmospheric carbon dioxide level continues its rise. Climate history shows that added atmospheric carbon dioxide has not had any significant influence on average global temperature. See graphs of NOAA and other credible data (all with source websites given) at http://www.middlebury.net/op-ed/pangburn.html at four different time scales up to 150,000 ybp.

THE current estimated GMT (actual) is 14C.
The anomaly 1970 -2008 is around +0.55C which as a linear trend is +0.18/decade.
If that trend continues in a linear fashion, then by 2108 the GMT will be 15.8C assuming all other things remain equal.
Not impressed.

It is unclear how the calculation at 15 was made. NOAA data is available at LINK and Hadley data at http://www.cru.uea.ac.uk/cru/data/temperature/hadcrut3gl.txt . These both show a trend of about +0.1 degree per decade. Although short term trends can be misleading, like the 22 year run up from 1976 to 1998, the dramatic drop of global average temperature in 2008 may be indicative of a change in character of the climate. The current UAH satellite numerical data (these data consist of the differences of lower atmospheric temperature from the 1979 thru 1998 average) is at http://vortex.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt . According to these data, the AVERAGE GLOBAL TEMPERATURE for the first 9 months of 2008 is LOWER than the average from 2000 thru 2007 by an amount equal to 43.1% of the total linearized increase (NOAA data) during the 20th century. Since 2000, the CARBON DIOXIDE LEVEL HAS INCREASED by 14.4% of the total increase since the start of the Industrial Revolution.

Dan: I just did a simple linear calc 0.18/decade for 10 decades = + 1.8c rise. Totally wrong I know but it was to illustrate a point that even if the 30 year trend continues in a linear fashion ( which it can't as the real effect is logarithmic) we would only see GMT rise to 15/16C by 2008.

1. I am intrigued by the slant, depending on the POV. Ie, if the temp is trending up, it is the result of manmade causes. However, a cold year (2008) is the result of natural causes (La Nina). Hmmm...

2. I'd be interested to see the variation in measuring points over the years, to confirm or reject the notion that some of the warming is due to the removal of Siberian monitoring stations after the USSR disintegration.

3. Looking at the charts for the last 10 or so years, it seems the warming is mostly concentrated in the far northern hemisphere. Would be interesting to see how that is explained.

Lee: have a look at the site posted by Saluki...it shows 2 out of 3 graphs indicating a temperature decline.
Also theWags has a valid point I raised some time ago...namely that the number of stations collecting data has declined alarmingly over the last 20 years, so we should be asking whether these graphs are truly representative of the global condition. See
http://www.uoguelph.ca/~rmckitri/research/nvst.html
for a graph of stations vs temperature. It also appears that too many of the remaining stations are in the US for a realistic sampling.

I think it is a bit disingenuous to use surface based temperature graphs rather than sattelite based ones. There is a new paper from one Arno Arak who claims that hte sattelites show no warming when measured to Dec 08. Is there anywhere this is refuted.

thewags
The far north has a couple of geologoc features that never seem to be talked about. The midatlantic ridge does not stop in the north atlantic but continues on under the Arctic ice pack. A paper last year stated that the activity had increased and that the ridge was spreading faster. The subduction zones are along the northern faces of Greenland to Alaska. So naturally the northernmost zones are showing increased volcanism. With all this increased tectonic activity I would expect major climate change at the north polar region. I truely can't understand why the IPCC has not taken this into account.

It has been cooling for ~8 yrs. Plotting a 11-y moving average conveniently allows you to ignore the last ~6 yr. Plotting a trailing 2-5 y average would catch the recent trend, which correlates with solar activity and most definitely does not correlate with the continuing increase in CO2. This website allows you to explore trends

first of all, the only thing we should be able to agree on, is that virtually nothing has been done so far to actually slow down climate change. for every Prius added to the road (which still runs entirely on fossil fuel), there's another new SUV. we've been talking about this issue, but doing virtually nothing.

where are the scared children? the younger generation is growing up with the same over-consumption habits as the older generations.

and who is "kept in poverty" by climate change science? an analysis of the recent proposed climate bill (going through the US house of reps) is that it would cost the average US family (not person) $175/yr by 2020. how does that amount keep anyone in poverty?

who is going to be "kept in poverty" if we do nothing are the poorest countries in the world, that already struggle to find enough water, and grow enough food, to meet demand. it's those countries that will be hardest hit by higher temperatures, not the cooler, wealthier northern powers. they'll be kept in poverty by those who refuse to act on climate change. not the other way around.

please don't twist the argument to make it seem like the skeptics are the ones standing up for the poor.

Since the year 2000, atmospheric carbon dioxide has increased 18.4% of the increase from 1800 to 2000. According to the average of the five reporting agencies, the trend of average global temperatures since 1998 shows no increase and from 2002 through 2008 the trend shows a DECREASE of 1.8°C/century. This SEPARATION (there have been many others) corroborates the lack of connection between atmospheric carbon dioxide increase and average global temperature. I wonder how wide the separation will need to get before the IPCC and a lot of others are forced to realize that maybe they missed something.

As the atmospheric carbon dioxide level continues to increase and the average global temperature doesn’t it is becoming more and more apparent that many Climate Scientists have made an egregious mistake and a whole lot of people have been misled.

Based on the data and graphs shown on this website ...www.climate4you.com ( under the section
" Global temperatures" ) there appears to have been little or no global warming since about 2003.

Observations based on the various graphs show according to my "eyeballed" interpretation :

University of Alabama data - No warming since 2003.

RSS - No warming since 2003

Hadcrut3 - No warming since 2003

NCDC - no warming since 2003

GISS - no warming since 2003

The temperature data on these graphs show a flat or declining trend from 2003 to the present. By "flat" I mean varying within less than say 0.05 of a degree from 2003 to 2007, which I would argue is well within the accuracy with which we can measure the global temperature of the Earth. Also bearing in mind that we are supposedly talking about and looking for the IPCC"s "catastrophic" global warming trend here. After 2007, the global temperatures as shown on these graphs seem to decline more abruptly.

Now my questions are: does anyone disagree with the data and trends shown on these graphs ? Does anyone disagree with my observations - and why ?

I note also that the graph posted above ( figure 2 ) also shows a flat temperature trend since 2002.

I suggest that the fill-in color areas under the lines in the total heat-content graph be removed. As experts in the graphic display of quantitative information often point out, such filling-in encourages the reader to compare the magnitudes of the areas under the curves rather than the actual graphed quantities -- giving an impression of a difference between the two quantities (in this case) that is roughly proportional to the square of the actual difference. In other words, the fill-in colors amount to inadvertent exaggeration (technically, they encourage ambiguity about whether one is comparing the curves or their integrals). Why give denialist critics even the slightest toe-hold? Simplify the graph. Trust people to get it without the big splashes of color.

Eyeballing the graphs it seems the gradients for each ENSO adjusted graph between 1910 -1944 and 1964-2005 are remarkably similar.
I would have expected the gradient to be related to the concentration of GG's and thus increase more in later years??

I haven't seen reference to the effect of heat of vaporization on the temperature of the oceans. Has this been done and, if so, what were the findings. It seems that since the Heat of Vaporization for water is 3.76 times greater than Heat of Fusion I would expect to see this factored in if melting the ice formations is.

Tim228,
i guess you refer to fig.1. The paper from which it is taken is an observational study, they measured the actual heat content of the oceans. Consequently the latent heat of evaporation of sea water as well as all the other energy related effects are automatically included.

I am fully on board with the argument that most of the heat is stored in the ocean, and that the atmosphere has a noisy temperature signal. However what I do not understand is the sharp drops in total energy content, for example around 1968 and 1996. Given constant or slowly rising CO2 concentration and the coean heat reservoir with a large time constant, I would have expected (naively perhaps) some monotonously rising function for total heat content.

Actually, Mizimi, when you graph the numbers, & draw a trendline, you see the rate of change for 1910-1944 was +0.013 degrees per year, wheras the rate of change for 1964-2005 was +0.016 degrees per year. So this 2nd warming period has been faster than the first one-even though average solar activity during the 2nd warming period has remained unchanged.

Mizimi & others seem to not understand the concept of the Energy Balance. Average Global Mean temperatures for all of 2000-2009 is +0.512, which is a full +0.18 degrees greater than the period of 1990-1999. This is in spite of the fact that the 1990's were dominated by rising sunspot numbers, wheras the current decade has been dominated by record low sunspot numbers (0 for almost the entirety of 2005-2009). Not only that, but the data shows that the rate of warming-per decade-is *accelerating*, not *decelerating*. Lastly, its all very well saying that Global Mean Temperatures will *only* rise by about 2 degrees over the next century (assuming no accelerating in the warming trend), but that is a GLOBAL MEAN. Actual temperature differentiations will be *much*, *much* higher at different parts of the year & at different points of the planet. Winter temperatures might only increase by an average of +0.1 to +0.5 degrees, wheras summer temperatures might increase by an average of 3 to 4 degrees-or more. Some parts of the globe may see a much sharper increase in mean temperatures-& see an increase in heat related disasters. Australia has had 3 record heat waves in the space of only a year, what can they expect in 10 to 20 years time? Also, I'd like to remind you that at least 2 civilizations were wiped out due to a total increase in global mean temperatures of only +0.6 degrees-over the space of almost 600 years. Tell the Anasazi & the Khmer Empire how unimpressed you are by a *mere* 1.8 degree increase in global mean temperatures over the next 100 years, Mizimi. Oh, thats right, you CAN'T because they got wiped out! Seriously, try quoting science instead of regurgitating fossil-fuel industry propaganda, I might then start taking you a little more seriously.

Look at this link for information on global warming stagnation since 2002: LINK The site is run by Ole Humlum, Professor of Physical Geography at the Department of Geosciences, University of Oslo. He says that "all five global temperature estimates presently show stagnation, at least since 2002. There has been no increase in global air temperature since 1998, which was affected by the oceanographic El Niño event. This does not exclude the possibility that global temperatures will begin to increase again later. On the other hand, it also remain a possibility that Earth just now is passing a temperature peak, and that global temperatures will begin to decrease within the coming 5-10 years. Only time will show which of these possibilities is the correct."

michaelkourlas,
temperature is not global warming, the trend in temperature is. And, as will be repeated over and over, short term trends has no meaning whatsoever, even just statistically. Look critically at the data shown, ask for the uncertainty in the determination of the trends, look at the determination coefficient (whre shown).

And take care, making hypothesis is easy untill you confront them with the known science. Any claim need to be justified quantitatively, which i can't see in the link you posted. Remember, climate change has (don't know why) a strong emotional impact on people, both "alarmists" and "deniers". The most conservative choice is stick to an expert advice, from climatologists; it's the very same thing we all do in our daily lives.

Try as the Mail did to spin the interview, there's really not much there.

Here's the part I found most shocking:

"Discussing the interview, the BBC’s environmental analyst Roger Harrabin said he had spoken to colleagues of Professor Jones who had told him that his strengths included integrity and doggedness but not record-keeping and office tidying."

Tut-tut. Lots of integrity but he can't keep his office tidy. Surely he must go.

Update. As I suspected but could not prove (yet), it was not what Jones said. Here's is the full quote from the original BBC interview:

"Question - Do you agree that from 1995 to the present there has been no statistically-significant global warming

Answer - Yes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level. The positive trend is quite close to the significance level. Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods. "

So, once again, at the Daily Mail they showed that they do not understand science but unrelentlessly continue to misguide they readers.

"Did global warming stop in 1998?" Did global warming START in 1998? U.S. Data Since 1895 Fail To Show Warming Trend LINK WASHINGTON, Jan. 25— After examining climate data extending back nearly 100 years, a team of Government scientists has concluded that there has been no significant change in average temperatures or rainfall in the United States over that entire period. While the nation's weather in individual years or even for periods of years has been hotter or cooler and drier or wetter than in other periods, the new study shows that over the last century there has been no trend in one direction or another. The study, made by scientists for the National Oceanic and Atmospheric Administration was published in the current issue of Geophysical Research Letters. It is based on temperature and precipitation readings taken at weather stations around the country from 1895 to 1987. ...

21 years ago that was the latest news. Almost quaint, but for some reason it's finding a lot of currency in the past few weeks. Here's some more of that same article, helping to provide full context:

"Dr. Kirby Hanson, the meteorologist who led the study, said in a telephone interview that the findings concerning the United States do not necessarily ''cast doubt'' on previous findings of a worldwide trend toward warmer temperatures, nor do they have a bearing one way or another on the theory that a buildup of pollutants is acting like a greenhouse and causing global warming. He said that the United States occupies only a small percentage of Earth's surface and that the new findings may be the result of regional variations.

...

Dr. Hanson of NOAA said today that the new study does not in any way contradict the findings reported by the NASA scientists and others. He said that his study, in which he was joined by George A. Maul and Thomas A. Karl, also of NOAA, looked at only the 48 contiguous states.

Dr. Hanson said that global warming caused by the greenhouse effect might have been countered by some cooling phenomenon that has not yet been identified and that the readings in his study recorded the net effect.

''We have to be careful about interpreting things like this,'' he said.

One aspect of the study that Dr. Hanson said was interesting was the finding that the urbanization of the United States has apparently not had a statistically significant effect on average temperature readings. A number of scientists have theorized that the replacement of forests and pastures by asphalt streets and concrete buildings, which retain heat, is an important cause of rising temperatures.

Dr. Hansen of NASA said today that he had ''no quarrel'' with the findings in the new study. He noted that the United States covered only 1.5 percent of Earth. ''If you have only one degree warming on a global average, how much do you get at random'' when taking measurements in such a relatively small area, he asked rhetorically.

''We are just arguing now about whether the global warming effect is large enough to see,'' he added. ''It is not suprising we are not seeing it in a region that covers only 1.5 percent of the globe.''

The earth is still storing up heat, but temperatures are not showing it? Well, that's a bit hard to swallow and sounds fishy. The new ocean temperature buoy system shows it's not the sea that's storing it, and that has such a large thermal inertia that you'd expect it to lag anyway. If the air and land is not warming... what's storing the heat? Dark matter in my backyard?? I think the statement is another stall to keep everyone from seeing that reality has diverged significantly from previous predictions. I've been living in the same area for sixty years. I haven't seen anything to indicate a climate change above normal variations. In fact, it's April 04, 32 F. outside and snowing right now!

Actually, the new ocean temperature buoy system (ARGO) does show that it's the sea that is storing up heat. The following is the measurement of ocean heat measured by ARGO down to 2000 metres deep and shows the oceans are steadily accumulating heat (von Schuckmann 2009):

Apologies for repeating the same graph from my response to comment #40 but it seems repetition is required for this particular argument.